UPDATE: I should’ve looked in the scientific literature first, but it seems that there really is no genetic basis for a taxonomic differentiation between Carduelis cabaret, C. flammea, and C. hornemanni, or any hybrids and sub-species. In other words, the three “species” of Redpoll (Lesser, common (mealy), and hoary, that we normally talk of as distinct are one in the same species. Lesser = Common = Hoary.
I bought a dedicated nijer feeder for the garden birds, filled it with the requisite seeds and hung it in our beech tree. It took no more than ten minutes for the Goldfinches (Carduelis carduelis) to spot it and start plucking the black seeds from the tiny holes in the metal feeder. This particular design has no perches common with others, perhaps to deter birds that need a perch, but not the Goldfinches one of which found he could be passerine on a nearby twig and easily reach across with his beak.
The Goldfinches will likely take the lion’s share, and these seeds are not cheap (pardon the pun), but not half an hour after I hung it a new visitor to the garden, a species I’d not seen anywhere before – Redpoll (Carduelis flammea (Common) or possibly the almost identical C. cabaret or the subspecies C. flammea cabaret is up for debate) another finch as you might have guessed from its scientific binomial. The bird doesn’t breed in the UK, it is a passage migrant and winter visitor; more commonly seen on the east coast.
Oh, and that red cap, apparently some don’t have red caps (it’s either a dietary or a genetic effect). Read about Goldpolls here.